The Three Charms R - The Twelve Monster Girls of Mahoroba

For some reason, the protagonist has got to live in the "Youkai Mountain". Which means he is always targeted by monster girls that suck mans lifeforce... Tentacles, slimy fluid, art of brainwashing... The monster girls seductions that incorporate magic will gradually grind down the protagonists will... Sometimes their acts of cumsuckery come with verbal abuses... And at other times he is courted and generously forced into "male-female relationship"...